Method and apparatus for producing flexible OLED device

ABSTRACT

After an intermediate region and a flexible substrate region of a plastic film of a multilayer stack are divided, the interface between the flexible substrate region and a glass base is irradiated with laser light. The multilayer stack is separated into the first portion and the second portion while the multilayer stack is kept in contact with the stage. The first portion includes a plurality of OLED devices in contact with the stage. The OLED devices include a plurality of functional layer regions and the flexible substrate region. The second portion includes the glass base and the intermediate region. The step of irradiating with the laser light includes forming the laser light from a plurality of arranged laser light sources and temporally and spatially modulating a power of the plurality of laser light sources according to a shape of the flexible substrate region of the synthetic resin film.

TECHNICAL FIELD

The present disclosure relates to a method and apparatus for producing aflexible OLED device.

BACKGROUND ART

A typical example of the flexible display includes a film which is madeof a synthetic resin such as polyimide (hereinafter, referred to as“plastic film”), and elements supported by the plastic film, such asTFTs (Thin Film Transistors) and OLEDs (Organic Light Emitting Diodes).The plastic film functions as a flexible substrate. The flexible displayis encapsulated with a gas barrier film (encapsulation film) because anorganic semiconductor layer which is a constituent of the OLED is likelyto deteriorate due to water vapor.

Production of the above-described flexible display is carried out usinga glass base on which a plastic film is formed over the upper surface.The glass base functions as a support (carrier) for keeping the shape ofthe plastic film flat during the production process. Elements such asTFTs and OLEDs, a gas barrier film, and the other constituents areformed on the plastic film, whereby the structure of a flexible OLEDdevice is realized while it is supported by the glass base. Thereafter,the flexible OLED device is delaminated from the glass base and gainsflexibility. The entirety of a portion in which elements such as TFTsand OLEDs are arrayed can be referred to as “functional layer region”.

According to the prior art, a sheet-like structure including a pluralityof flexible OLED devices is delaminated from a glass base, andthereafter, optical parts and other constituents are mounted to thissheet-like structure. Thereafter, the sheet-like structure is dividedinto a plurality of flexible devices. This cutting is realized by, forexample, laser beam irradiation.

Patent Document No. 1 discloses the method of irradiating the interfacebetween each flexible OLED device and the glass base with laser light(lift-off light) in order to delaminate each flexible OLED device fromthe glass base (supporting substrate). According to the method disclosedin Patent Document No. 1, after irradiation with the lift-off light,respective flexible OLED devices are divided from one another, and eachof the flexible OLED devices is delaminated from the glass base.

CITATION LIST Patent Literature

Patent Document No. 1: Japanese Laid-Open Patent Publication No.2014-48619

SUMMARY OF INVENTION Technical Problem

According to the conventional production method, the cutting by means oflaser beam irradiation is carried out after expensive parts, forexample, encapsulation film, polarizer, and/or heat radiation sheet, aremounted to a sheet-like structure including a plurality of flexible OLEDdevices. Therefore, unnecessary portions divided by laser beamirradiation, i.e., portions which are not to be constituents of a finalOLED device, are quite useless. Also, there is a problem that, afterbeing delaminated from the glass base, it is difficult to handle aplurality of flexible OLED devices which have no rigidity.

The present disclosure provides a method and apparatus for producing aflexible OLED device which are capable of solving the above-describedproblems.

Solution to Problem

The flexible OLED device production method of the present disclosureincludes, in an exemplary embodiment: providing a multilayer stack whichhas a first surface and a second surface, the multilayer stack includinga glass base which defines the first surface, a functional layer regionincluding a TFT layer and an OLED layer, a synthetic resin film providedbetween the glass base and the functional layer region and bound to theglass base, the synthetic resin film including a flexible substrateregion supporting the functional layer region and an intermediate regionsurrounding the flexible substrate region, and a protection sheet whichcovers the functional layer region and which defines the second surface;dividing the intermediate region and the flexible substrate region ofthe synthetic resin film from each other; irradiating an interfacebetween the synthetic resin film and the glass base with laser light;and separating the multilayer stack into a first portion and a secondportion by increasing a distance from a stage to the glass base whilethe second surface of the multilayer stack is kept in contact with thestage. The first portion of the multilayer stack includes an OLED devicewhich is in contact with the stage, the OLED device including thefunctional layer region and the flexible substrate region of thesynthetic resin film. The second portion of the multilayer stackincludes the glass base and the intermediate region of the syntheticresin film. Irradiating the interface between the synthetic resin filmand the glass base with the laser light includes forming the laser lightfrom a plurality of arranged laser light sources and temporally andspatially modulating a power of the plurality of laser light sourcesaccording to a shape of the flexible substrate region of the syntheticresin film such that an irradiation intensity of the laser light for atleast part of an interface between the intermediate region of thesynthetic resin film and the glass base is lower than an irradiationintensity of the laser light for the interface between the flexiblesubstrate region of the synthetic resin film and the glass base.

In one embodiment, a shape of the flexible substrate region of thesynthetic resin film has a cutout, a protrusion, and/or a curved contourwhen viewed in a direction perpendicular to the first surface.

In one embodiment, a number of the flexible substrate region of thesynthetic resin film is plural, and a number of the OLED device includedin the first portion of the multilayer stack is plural.

In one embodiment, the plurality of laser light sources are a pluralityof semiconductor laser devices, and irradiating the interface betweenthe synthetic resin film and the glass base with the laser lightincludes modulating a driving current flowing through each of theplurality of semiconductor laser devices, thereby temporally andspatially modulating the irradiation intensity of the laser light.

In one embodiment, the plurality of semiconductor laser devices arearranged in a single row or a plurality of rows, and an arrangementpitch of the plurality of semiconductor laser devices is in a range ofnot less than 1 mm and not more than 5 mm.

In one embodiment, the laser light is a line beam extending in a firstdirection which is parallel to a perimeter of the glass base, andirradiating the interface between the synthetic resin film and the glassbase with the laser light includes moving an irradiation region on theinterface which is to be irradiated with the laser light in a seconddirection which is transverse to the first direction.

In one embodiment, the at least part of the interface between theintermediate region of the synthetic resin film and the glass baseincludes a plurality of parallel stripe regions extending in the firstdirection, and any of the plurality of parallel stripe regions includesa large-width portion and/or a narrow-width portion.

In one embodiment, the at least part of the interface between theintermediate region of the synthetic resin film and the glass baseincludes a plurality of parallel stripe regions extending in the seconddirection, and any of the plurality of parallel stripe regions includesa large-width portion and/or a narrow-width portion.

In one embodiment, the at least part of the interface between theintermediate region of the synthetic resin film and the glass base has awidth which is not less than 50% of a width of the intermediate region.

In one embodiment, the at least part of the interface between theintermediate region of the synthetic resin film and the glass base has awidth which is not less than 1 mm.

In one embodiment, the difference between an irradiation intensity ofthe laser light in the at least part of the interface between theintermediate region of the synthetic resin film and the glass base andan irradiation intensity of the laser light for the interface betweenthe flexible substrate region of the synthetic resin film and the glassbase is not less than 50 mJ/cm².

In one embodiment, the method further includes, after separating themultilayer stack into the first portion and the second portion,performing a process on the OLED device which is in contact with thestage.

The flexible OLED device production apparatus of the present disclosureincludes, in an exemplary embodiment: a stage for supporting amultilayer stack which has a first surface and a second surface, themultilayer stack including a glass base which defines the first surface,a functional layer region including a TFT layer and an OLED layer, asynthetic resin film provided between the glass base and the functionallayer region and bound to the glass base, the synthetic resin filmincluding a flexible substrate region supporting the functional layerregion and an intermediate region surrounding the flexible substrateregion, and a protection sheet which covers the functional layer regionand which defines the second surface, the intermediate region and theflexible substrate region of the synthetic resin film being divided fromeach other; and a lift-off light irradiation unit for irradiating withlaser light an interface between the synthetic resin film and the glassbase in the multilayer stack supported by the stage. The lift-off lightirradiation unit includes a plurality of arranged laser light sourcesfor forming the laser light. The lift-off light irradiation unittemporally and spatially modulates a power of the plurality of laserlight sources according to a shape of the flexible substrate region ofthe synthetic resin film such that an irradiation intensity of the laserlight for at least part of an interface between the intermediate regionof the synthetic resin film and the glass base is lower than anirradiation intensity of the laser light for the interface between theflexible substrate region of the synthetic resin film and the glassbase.

In one embodiment, the plurality of laser light sources are a pluralityof semiconductor laser devices, and the lift-off light irradiation unitincludes a laser driving circuit for modulating a driving currentflowing through each of the plurality of semiconductor laser devices,thereby temporally and spatially modulating the irradiation intensity ofthe laser light.

In one embodiment, the plurality of semiconductor laser devices arearranged in a single row or a plurality of rows, and an arrangementpitch of the plurality of semiconductor laser devices is in a range ofnot less than 1 mm and not more than 5 mm.

In one embodiment, the apparatus further includes an actuator forincreasing a distance from the stage to the glass base while the stageis kept in contact with the second surface of the multilayer stack,thereby separating the multilayer stack into a first portion and asecond portion, wherein the first portion of the multilayer stackincludes an OLED device which is in contact with the stage, the OLEDdevice including the functional layer region and the flexible substrateregion of the synthetic resin film, and the second portion of themultilayer stack includes the glass base and the intermediate region ofthe synthetic resin film.

Advantageous Effects of Invention

According to an embodiment of the present invention, a novel method forproducing a flexible OLED device which is capable of solving theabove-described problems is provided.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A is a plan view showing a configuration example of a multilayerstack used in a flexible OLED device production method of the presentdisclosure.

FIG. 1B is a cross-sectional view of the multilayer stack taken alongline B-B of FIG. 1A.

FIG. 1C is a plan view showing a configuration example of a plastic filmin the multilayer stack.

FIG. 1D is a plan view showing another configuration example of aplastic film in the multilayer stack.

FIG. 1E is a cross-sectional view showing another example of themultilayer stack.

FIG. 1F is a cross-sectional view showing still another example of themultilayer stack.

FIG. 2 is a cross-sectional view schematically showing the dividingpositions in the multilayer stack.

FIG. 3A is a diagram schematically showing a state immediately before astage supports a multilayer stack.

FIG. 3B is a diagram schematically showing a state where the stagesupports the multilayer stack.

FIG. 3C is a diagram schematically showing that the interface between aglass base and a plastic film of the multilayer stack with laser light(lift-off light).

FIG. 4 is a perspective view schematically showing irradiation of amultilayer stack with laser light (lift-off light) emitted from a laserlight source of a lift-off light irradiation unit.

FIG. 5 is a block diagram schematically showing the flow of signals,data and instructions in the lift-off light irradiation unit.

FIG. 6 is a perspective view schematically showing a basic configurationof a semiconductor laser device which can be used in a line beam source.

FIG. 7A is a diagram schematically showing a configuration example of aline beam source and an example of the light intensity distribution oflaser light emitted from a semiconductor laser device during scanning.

FIG. 7B is a diagram schematically showing a configuration example of aline beam source and another example of the light intensity distributionof laser light emitted from a semiconductor laser device duringscanning.

FIG. 8 is a perspective view schematically showing another configurationexample of the line beam source.

FIG. 9 is a diagram schematically showing an example of the distributionin the Y-axis direction of the irradiation intensity of the lift-offlight.

FIG. 10 is a diagram schematically showing another example of thedistribution in the Y-axis direction of the irradiation intensity of thelift-off light.

FIG. 11 is a diagram schematically showing still another example of thedistribution in the Y-axis direction of the irradiation intensity of thelift-off light.

FIG. 12 is a diagram schematically showing still another example of thedistribution in the Y-axis direction of the irradiation intensity of thelift-off light.

FIG. 13 is a diagram schematically showing an example of thedistribution in the X-axis direction (scanning direction) of theirradiation intensity of the lift-off light.

FIG. 14 is a diagram schematically showing another example of thedistribution in the X-axis direction of the irradiation intensity of thelift-off light.

FIG. 15A is a diagram schematically showing still another example of thedistribution in the X-axis direction of the irradiation intensity of thelift-off light.

FIG. 15B is a diagram schematically showing still another example of thedistribution in the X-axis direction of the irradiation intensity of thelift-off light.

FIG. 16A is a cross-sectional view schematically showing the multilayerstack before the multilayer stack is separated into the first portionand the second portion after irradiation with lift-off light.

FIG. 16B is a cross-sectional view schematically showing the multilayerstack separated into the first portion and the second portion.

FIG. 17 is a perspective view showing the glass base separated from themultilayer stack by an LLO unit.

FIG. 18 is a perspective view showing removal of the glass base from thestage.

FIG. 19 is a perspective view showing the stage from which the glassbase has been removed.

FIG. 20 is a cross-sectional view showing the stage from which the glassbase has been removed.

FIG. 21 is a cross-sectional view showing flexible OLED devices detachedfrom the stage.

FIG. 22 is a cross-sectional view showing another protection sheet boundto a plurality of OLED devices which are in contact with the stage.

FIG. 23 is a cross-sectional view showing a carrier sheet carrying aplurality of parts which are to be mounted to the plurality of OLEDdevices.

FIG. 24A is a cross-sectional view illustrating a step of the flexibleOLED device production method in an embodiment of the presentdisclosure.

FIG. 24B is a cross-sectional view illustrating a step of the flexibleOLED device production method in an embodiment of the presentdisclosure.

FIG. 24C is a cross-sectional view illustrating a step of the flexibleOLED device production method in an embodiment of the presentdisclosure.

FIG. 24D is a cross-sectional view illustrating a step of the flexibleOLED device production method in an embodiment of the presentdisclosure.

FIG. 25 is an equivalent circuit diagram of a single sub-pixel in aflexible OLED device.

FIG. 26 is a perspective view of the multilayer stack in the middle ofthe production process.

DESCRIPTION OF EMBODIMENTS

An embodiment of a method and apparatus for producing a flexible OLEDdevice of the present disclosure is described with reference to thedrawings. In the following description, unnecessarily detaileddescription will be omitted. For example, detailed description ofwell-known matter and repetitive description of substantially identicalelements will be omitted. This is for the purpose of avoiding thefollowing description from being unnecessarily redundant and assistingthose skilled in the art to easily understand the description. Thepresent inventors provide the attached drawings and the followingdescription for the purpose of assisting those skilled in the art tofully understand the present disclosure. Providing these drawings anddescription does not intend to limit the subject matter recited in theclaims.

<Multilayer Stack>

See FIG. 1A and FIG. 1B. In a flexible OLED device production method ofthe present embodiment, firstly, a multilayer stack 100 illustrated inFIG. 1A and FIG. 1B is provided. FIG. 1A is a plan view of themultilayer stack 100. FIG. 1B is a cross-sectional view of themultilayer stack 100 taken along line B-B of FIG. 1A. In FIG. 1A andFIG. 1B, an XYZ coordinate system with X-axis, Y-axis and Z-axis, whichare perpendicular to one another, is shown for reference.

The multilayer stack 100 includes a glass base (motherboard or carrier)10, a plurality of functional layer regions 20 each including a TFTlayer 20A and an OLED layer 20B, a synthetic resin film (hereinafter,simply referred to as “plastic film”) 30 provided between the glass base10 and the plurality of functional layer regions 20 and bound to theglass base 10, and a protection sheet 50 covering the plurality offunctional layer regions 20. The multilayer stack 100 further includes agas barrier film 40 provided between the plurality of functional layerregions 20 and the protection sheet 50 so as to cover the entirety ofthe functional layer regions 20. The multilayer stack 100 may includeanother unshown layer, such as a buffer layer.

The first surface 100 a of the multilayer stack 100 is defined by theglass base 10. The second surface 100 b of the multilayer stack 100 isdefined by the protection sheet 50. The glass base 10 and the protectionsheet 50 are materials temporarily used in the production process butare not constituents of a final flexible OLED device.

The plastic film 30 shown in the drawings includes a plurality offlexible substrate regions 30 d respectively supporting the plurality offunctional layer regions 20, and an intermediate region 30 i surroundingeach of the flexible substrate regions 30 d. The flexible substrateregions 30 d and the intermediate region 30 i are merely differentportions of a single continuous plastic film 30 and do not need to bephysically distinguished. In other words, regions of the plastic film 30lying immediately under respective ones of the functional layer regions20 are the flexible substrate regions 30 d, and the other region of theplastic film 30 is the intermediate region 30 i.

Each of the plurality of functional layer regions 20 is a constituent ofa final flexible OLED device. In other words, the multilayer stack 100has such a structure that a plurality of flexible OLED devices which arenot yet divided from one another are supported by a single glass base10. Each of the functional layer regions 20 has such a shape that, forexample, the thickness (size in Z-axis direction) is several tens ofmicrometers, the length (size in X-axis direction) is about 12 cm, andthe width (size in Y-axis direction) is about 7 cm. These sizes can beset to arbitrary values according to the required largeness of thedisplay screen.

Next, a configuration example of the flexible substrate regions 30 d andthe intermediate region 30 i of the present embodiment is described inmore detail with reference to FIG. 1C. FIG. 1C is a plan view showing anexample of the layout of the flexible substrate regions 30 d and theintermediate region 30 i of the plastic film 30 of the presentembodiment.

In the example illustrated in the drawing, the shape of each of theflexible substrate regions 30 d includes a cutout 30U, protrusions 30V,and curved contour portions 30W. The shape of the flexible substrateregions 30 d is conformable to the shape of the flexible OLED devicesshown in FIG. 1A. In the present embodiment, the flexible OLED deviceshave a shape different from a simple rectangle. This shape isconformable to the design of an electronic device to which anarrow-frame flexible OLED device is mounted as a display device, suchas smartphone, tablet computer, and television set. More specifically,in addition to the display device, parts, such as camera, loudspeaker,and physical switch, can be mounted to such an electronic device. Thecutout 30U of the flexible substrate regions 30 d shown in FIG. 1C canbe provided in a region in which such parts are to be placed.

The plurality of flexible substrate regions 30 d are two-dimensionallyarrayed in rows and columns according to the arrangement ofcorresponding flexible OLED devices. The intermediate region 30 iconsists of a plurality of stripes perpendicular to one another andforms a grid pattern. The stripes can include large-width portions andnarrow-width portions which accord with the recesses and protrusions ofthe flexible substrate regions 30 d. In the present embodiment, thewidth of each stripe is, for example, about 1-10 mm. The flexiblesubstrate region 30 d of the plastic film 30 functions as the “flexiblesubstrate” in each flexible OLED device which is in the form of a finalproduct. Meanwhile, the intermediate region 30 i of the plastic film 30is not a constituent of the final product.

In an embodiment of the present disclosure, the configuration of themultilayer stack 100 is not limited to the example illustrated in thedrawings. The number of functional layer regions 20 (the number of OLEDdevices) supported by a single glass base 10 does not need to be pluralbut may be singular. If the number of functional layer regions 20 issingular, the intermediate region 30 i of the plastic film 30 forms asimple frame pattern surrounding a single functional layer region 20.

FIG. 1D is a plan view showing a configuration example of the plasticfilm 30 where the number of OLED devices supported by a single glassbase 10 is one. In this example, the shape of the flexible substrateregion 30 d has a cutout 30U and a protrusion 30V. The shape of thisflexible substrate region 30 d is conformable to the shape of a flexibleOLED device which can be used for a large-sized television set ormonitor. The cutout 30U of the flexible substrate region 30 d can beprovided in a region in which parts, such as camera, loudspeaker, andphysical switch, are to be placed. In this example, a single flexibleOLED device can be formed on a glass base 10 which has the size of, forexample, 1.5 m×0.9 m.

The size or proportion of each component illustrated in respectivedrawings is determined from the viewpoint of understandability. Theactual size or proportion is not necessarily reflected in the drawings.

The multilayer stack 100 which can be used in the production method ofthe present disclosure is not limited to the example illustrated in FIG.1A and FIG. 1B. FIG. 1E and FIG. 1F are cross-sectional views showingother examples of the multilayer stack 100. In the example illustratedFIG. 1E, the protection sheet 50 covers the entirety of the plastic film30 and extends outward beyond the plastic film 30. In the exampleillustrated FIG. 11, the protection sheet 50 covers the entirety of theplastic film 30 and extends outward beyond the glass base 10. As will bedescribed later, after the glass base 10 is separated from themultilayer stack 100, the multilayer stack 100 is a thin flexiblesheet-like structure which has no rigidity. The protection sheet 50serves to protect the functional layer regions 20 from impact andabrasion when the functional layer regions 20 collide with or come intocontact with external apparatuses or instruments in the step ofdelaminating the glass base 10 and the steps after the delaminating.Since the protection sheet 50 is peeled off from the multilayer stack100 in the end, a typical example of the protection sheet 50 has alaminate structure which includes an adhesive layer of a relativelysmall adhesive force (a layer of an applied mold-releasing agent) overits surface. The more detailed description of the multilayer stack 100will be described later.

<Dividing of OLED Devices>

According to the flexible OLED device production method of the presentembodiment, after the step of providing the above-described multilayerstack 100, the step of dividing an intermediate region 30 i andrespective ones of a plurality of flexible substrate regions 30 d of theplastic film 30 from one another is carried out.

FIG. 2 is a cross-sectional view schematically showing the positions fordividing the intermediate region 30 i and respective ones of theplurality of flexible substrate regions 30 d of the plastic film 30 fromone another. The positions of irradiation extend along the periphery ofeach of the flexible substrate regions 30 d. In FIG. 2, the positionsindicated by arrows are irradiated with a laser beam for cutting. Partof the multilayer stack 100 exclusive of the glass base 10 is cut into aplurality of OLED devices 1000 and the remaining unnecessary portions.By cutting, a gap of several tens of micrometers to several hundreds ofmicrometers is formed between each of the OLED devices 1000 and aportion surrounding the OLED device 1000. The cutting can also berealized by a dicing saw instead of the laser beam irradiation. Sincethe periphery of the flexible substrate regions 30 d has complicatedrecesses and protrusions and curves as shown in FIG. 1C, the cutting isdesirably realized by the laser beam irradiation. After the cutting, theOLEO devices 1000 and the remaining unnecessary portions remain bound tothe glass base 10.

When the cutting is realized by a laser beam, the wavelength of thelaser beam may be in any of the infrared, visible and ultraviolet bands.From the viewpoint of reducing the effect of the cutting on the glassbase 10, the laser beam desirably has a wavelength in the range of greento ultraviolet. For example, when a Nd:YAG laser device is used, thecutting can be carried out using a second harmonic wave (wavelength: 532nm) or a third harmonic wave (wavelength: 343 nm or 355 nm). In such acase, the laser power is adjusted to 1 to 3 watts, and the scanning rateis set to about 500 mm per second, so that the multilayer structuresupported by the glass base 10 can be cut (divided) into OLED devicesand unnecessary portions without damaging the glass base 10.

According to the embodiment of the present disclosure, the timing of theabove-described cutting is earlier than in the prior art. Since thecutting is carried out while the plastic film 30 is bound to the glassbase 10, alignment for the cutting can be made with high precision andaccuracy even if the gap between adjoining OLED devices 1000 is narrow.Thus, the gap between adjoining OLED devices 1000 can be shortened, andaccordingly, useless portions which are unnecessary for a final productcan be reduced. In the prior art, after the delaminating from the glassbase 10, a polarizer, a heat radiation sneer, and/or an electromagneticshield can be adhered to the plastic film 30 so as to cover the entiretyof the surface (delaminated surface) of the plastic film 30. In such acase, the polarizer, the heat radiation sheet, and/or theelectromagnetic shield are also divided by cutting into portionscovering the OLED devices 1000 and the remaining unnecessary portions.The unnecessary portions are disposed of as waste. On the other hand,according to the production method of the present disclosure, productionof such waste can be suppressed as will be described later.

<Lift-Off Light Irradiation>

After the intermediate region 30 i and respective ones of the pluralityof flexible substrate regions 30 d of the plastic film 30 are dividedfrom one another, the step of irradiating the interface between theflexible substrate regions 30 d of the plastic film 30 and the glassbase 10 with laser light is carried out using a lift-off lightirradiation unit.

FIG. 3A schematically shows a state immediately before the stage 210supports the multilayer stack 100. In the present embodiment, the stage210 is a chuck stage which has a large number of pores in the surfacefor suction. The multilayer stack 100 is arranged such that the secondsurface 100 b of the multilayer stack 100 faces the surface 210S of thestage 210, and is supported by the stage 210.

FIG. 3B schematically shows a state where the stage 210 supports themultilayer stack 100. The arrangement of the stage 210 and themultilayer stack 100 is not limited to the example illustrated in thedrawing. For example, the multilayer stack 100 may be placed upside downsuch that the stage 210 is present under the multilayer stack 100.

In the example illustrated in FIG. 3B, the multilayer stack 100 is incontact with the surface 210S of the stage 210, and the stage 210 holdsthe multilayer stack 100 by suction.

Then, as shown in FIG. 3C, the interface between the plastic film 30 andthe glass base 10 is irradiated with laser light (lift-off light) 216.FIG. 3C schematically illustrates irradiation of the interface betweenthe glass base 10 and the plastic film 30 of the multilayer stack 100with the lift-off light 216 in the shape of a line extending in adirection vertical to the sheet of the drawing. A part of the plasticfilm 30 at the interface between the glass base 10 and the plastic film30 absorbs the lift-off light 216 and decomposes (disappears). Byscanning the above-described interface with the lift-off light 216, thedegree of binding of the plastic film 30 to the glass base 10 isreduced. The wavelength of the lift-off light 216 is typically in theultraviolet band. The wavelength of the lift-off light 216 is selectedsuch that the lift-off light 216 is hardly absorbed by the glass base 10but is absorbed by the plastic film 30 as much as possible. The lightabsorption by the glass base 10 is, for example, about 10% in thewavelength range of 343-355 nm but can increase to 30-60% at 308 nm.

Hereinafter, lift-off light irradiation according to the presentembodiment is described in detail.

<Lift-Off Light Irradiation Unit>

In the present embodiment, the lift-off light irradiation unit includesa line beam source for emitting lift-off light 216. The line beam sourceincludes a laser device and a plurality of arranged laser light sources.A typical example of the laser light sources is a semiconductor laserdevice (laser diode). In the present disclosure, the lift-off lightirradiation unit is referred to as “laser lift-off (LLO) unit”.

FIG. 4 is a perspective view schematically showing irradiation of themultilayer stack 100 with a line beam (lift-off light 216) emitted fromthe line beam source 214 of a LLO unit 220 of the present embodiment.For the sake of understandability, the stage 210, the multilayer stack100 and the line beam source 214 are shown as being spaced away from oneanother in the Z-axis direction of the drawing. During irradiation withthe lift-off light 216, the second surface 100 b of the multilayer stack100 is in contact with the stage 210.

The LLO unit 220 illustrated in FIG. 4 includes a transporting device230 for moving the line beam source 214 such that the irradiationposition of the line beam on the multilayer stack 100 moves in adirection transverse to the line beam (scanning direction). Thetransporting device 230 illustrated in the drawing includes a supportingbase 270 and a guide rail 246 for guiding the movement of the line beamsource 214. The transporting device 230 includes an actuator such as,for example, a motor and is capable of moving the line beam source 214.The motor may be a rotating electric machine, such as DC motor,three-phase AC motor, stepping motor, or may be a linear motor or anultrasonic motor. When an ultrasonic motor is used, highly-accuratepositioning is possible as compared with the other types of motors.Further, the ultrasonic motor provides large holding power when it isnot moving, and can hold without supply of electric power. Therefore,the heat generation is small when it is not moving.

Next, see FIG. 5. FIG. 5 is a block diagram schematically showing theflow of signals, data and instructions in the LLO unit 220.

The controller 260 is typically a computer. A part or the entirety ofthe controller 260 can be a general-purpose or special-purpose computersystem. The computer system includes an OS (operating system) and, whennecessary, hardware devices such as peripheral devices. The controller260 is connected with a memory 274 which is a computer-readable storagemedium. In the memory 274, a program is stored which defines theoperation of the LLO unit 220.

In FIG. 5, for the sake of simplicity, a single memory unit is shown.However, the actual memory 274 can consist of a plurality of storagedevices of an identical type or different types. A part of the memory274 may be a nonvolatile memory while the other part may be a randomaccess memory. A part or the entirety of the memory 274 may be aneasily-detachable optical disc or solid-state recording element or maybe a cloud-type storage on a net multilayer stack.

The controller 260 is connected with a sensor 276, such as temperaturesensor and image sensor. Such a sensor 276 enables detection of theirradiation position of the line beam on the multilayer stack 100 ormonitoring of a physical or chemical change in the multilayer stack 100which can be caused by irradiation.

The controller 260 follows the program stored in the memory 274 andissues appropriate instructions to a laser driving circuit (LD drivingcircuit) 280 and a transporting device driving circuit 290, whennecessary, based on the output of the sensor 276. The LD driving circuit280 adjusts the irradiation intensity of the line beam emitted from theline beam source 214 according to the instruction from the controller260. The transporting device driving circuit 290 adjusts the operationof the transporting device 230 according to the instruction from thecontroller 260.

The transporting device driving circuit 290 controls, for example, therotation angle and the rotation speed of the motor in order to adjustthe mutual positional relationship between the line beam source 214 andthe stage 210. In this example, for the sake of simplicity, the linebeam source 214 moves in the X-axis direction while the stage 210 isfixed, although the LLO unit of the present embodiment is not limited tothis example. The stage 210 may move while the line beam source 214 isfixed. Alternatively, both the stage 210 and the line beam source 214may move in an identical direction or in different directions. When thestage 210 moves while the stage 210 supports a heavy-weight multilayerstack 100, a bearing such as, for example, air slider can be used.

The line beam source 214 includes a plurality of arranged semiconductorlaser devices. Each of the semiconductor laser devices is connected witha laser diode (LD) driving circuit 280. The LD driving circuit 280receives an electric signal from the above-described photodiode formonitoring and adjusts the optical power of the semiconductor laserdevice to a predetermined level.

<Semiconductor Laser Device>

FIG. 6 is a perspective view schematically showing a basic configurationof a semiconductor laser device which can be used in the line beamsource 214. The semiconductor laser device 300 shown in FIG. 6 includesa semiconductor multilayer stack 322 which has a facet 326 a. The facet326 a includes an emission region (emitter) 324 from which laser lightis to be emitted. In this example, the semiconductor multilayer stack322 is supported on a semiconductor substrate 320 and includes a p-sidecladding layer 322 a, an active layer 322 b, and an n-side claddinglayer 322 c. On the upper surface 326 b of the semiconductor multilayerstack 322, a p-side electrode 312 in the shape of a stripe is provided.On the rear surface of the semiconductor substrate 320, an n-sideelectrode 316 is provided. When an electric current which is greaterthan a threshold flows through a predetermined region of the activelayer 322 b from the p-side electrode 312 to the n-side electrode 316,laser oscillation occurs. The facet 326 a of the semiconductormultilayer stack 322 is covered with an unshown reflective film. Laserlight is emitted from the emission region 324 via the reflective film.

In general, a size in the Y-axis direction of the emission region 324,Ey, is smaller than a size in the X-axis direction of the emissionregion 324, Ex. Thus, laser light emitted from the emission region 324diverges in the Y-axis direction due to a diffraction effect. Accordingto the embodiment of the present disclosure, formation of a line beamcan be realized by utilizing this diffraction effect. Note that anoptical element, such as lens, diffraction element, slit, may beprovided over the front surface of the emission region 324 for beamreshaping of the laser light.

The semiconductor laser device 300 can be made of various semiconductormaterials and can have various configurations and sizes according to theoscillation wavelength and the optical power. When the laser light isrequired to have a wavelength in the ultraviolet region (e.g., 300-350nm), the semiconductor muitilayer stack 322 of the semiconductor laserdevice 300 can be suitably made of a nitride semiconductor, such asAlGaN-based semiconductor or InAlGaN-based semiconductor. Theoscillation wavelength of the semiconductor laser device 300 can be setwithin the range of, for example, 200 nm to 350 nm. A ridge stripe maybe provided in the p-side cladding layer 322 a such that lightconfinement in the horizontal transverse direction is realized. Theactive layer 322 b may include a single or a plurality of quantum wellstructures. The semiconductor multilayer stack 322 may include othersemiconductor layers, such as a light guiding layer, a buffer layer, anda contact layer. When the substrate 320 is a sapphire substrate, then-side electrode 316 is provided on a side of the substrate 320 on whichthe p-side electrode 312 is provided.

The configuration shown in FIG. 6 is merely a typical example of theconfiguration of the semiconductor laser device 300 and is simplifiedfor the sake of simple description. This simplified configurationexample does not limit embodiments of the present disclosure. The linebeam can also be formed using a surface-emission type semiconductorlaser device. Note that, in the other drawings, constituents such as then-side electrode 316 will be omitted for the sake of simplicity.

<Configuration Example of Line Beam Source>

See FIG. 7A. The line beam source 214 includes a plurality ofsemiconductor laser devices 300 and a plurality of supports 214Asupporting the semiconductor laser devices 300. The semiconductor laserdevices 300 and the supports 214A are held in a casing 214B. Thesupports 214A may be suitably made of a good conductor of high thermalconductivity, e.g., a metal such as copper or a ceramic material such asaluminum nitride. The casing 214B is closed with, for example, anunshown light-transmitting cover, whereby the inside of the casing 214Bcan be shielded from the atmosphere. The inside of the casing 214B isfilled with, for example, a gas which is inert with the semiconductorlaser devices 300. Each of the semiconductor laser devices 300 issupplied with electric power via an unshown wire (metal wire, metalribbon, or the like). To suppress increase of the temperature of thesemiconductor laser devices 300 during operation, a thermoelectriccooling device (not shown) such as Peltier device may be provided nearthe semiconductor laser devices 300. The supports 214A may include aninternal channel for water cooling and fins for air cooling.

In each of the semiconductor laser devices 300, an unshown photodiode isprovided near a facet 326 c of the semiconductor laser device 300 whichis opposite to the emission-side facet 326 a. This facet 326 c iscovered with a reflective film which has a relatively-high reflectance.However, part of laser light oscillating inside the semiconductor laserdevice 300 leaks out from the facet 326 c. This laser light leakage isdetected by the photodiode, whereby the intensity of laser light emittedfrom the facet 326 a can be monitored. The output of the photodiode isused for power control as previously described.

In the example of FIG. 7A, eleven semiconductor laser devices 300 arearranged along an identical line which is parallel to the Y-axis. Thenumber of semiconductor laser devices 300 is not limited to this examplebut may be not more than ten or may be not less than twelve. To form along line beam for irradiating a large-area region or to modulate thespatial distribution of the irradiation intensity at high resolution,more than 50 or more than 100 semiconductor laser devices 300 can bearranged on the same line. Each of the semiconductor laser devices 300can have the same configuration as that of the semiconductor laserdevice 300 of FIG. 6. Laser light (lift-off light 216) emitted from theemission regions 324 of respective ones of the semiconductor laserdevices 300 diverge in parallel to the same line so as to form a linebeam.

In FIG. 7A, a rectangular scanned surface SC which is parallel to the XYplane and an irradiation region 218 which is formed by laser light(lift-off light 216) on the scanned surface SC are schematically shown.The scanned surface SC is equivalent to the interface between theplastic film 30 and the glass base 10 in the multilayer stack 100.

For the sake of reference, FIG. 7A shows the X-axis directiondistribution and the Y-axis direction distribution of the irradiationintensity IS in the irradiation region 218 at a certain time. The X-axisdirection distribution of the irradiation intensity IS is narrow andunimodal. Meanwhile, the Y-axis direction distribution of theirradiation intensity IS has eleven peaks because laser light emittedfrom respective ones of the eleven semiconductor laser devices 300overlap one another and extend in the shape of a line.

As previously described, laser light emitted from each of thesemiconductor laser devices 300 has a tendency to diverge in apredetermined direction (in this example, Y-axis direction) due to adiffraction effect. This characteristic is suitable to formation of aline beam extending in the Y-axis direction. Meanwhile, an opticalelement such as cylindrical lens may be used in order to suppress thedivergence in the X-axis direction such that the irradiation energy inevery second per unit area (irradiation intensity expressed injoule/cm²) is increased. When such an optical element is used to focusthe laser light in the X-axis direction, the width (the size in theX-axis direction) of the irradiation region 218 on the scanned surfaceSC can be narrowed to, for example, about 0.2 mm or smaller.

From the viewpoint of increasing the irradiation intensity of the linebeam, it is preferred to decrease the arrangement pitch of thesemiconductor laser devices 300 such that the number density of thesemiconductor laser devices 300 is increased. For example, 100 or moresemiconductor laser devices 300 may be arranged in a straight line atintervals of 1 mm to 5 mm (arrangement pitch: the distance between thecenters of adjoining light sources). When the semiconductor laserdevices 300 are arranged at such a high density and the distance fromthe semiconductor laser devices 300 to the scanned surface SC is forexample 10 mm, the irradiation intensity can be modulated at a highspatial resolution of, for example, 1 mm to 5 mm. To achieve a highspatial resolution, an optical element which can prevent the crosssection of laser light emitted from each of the semiconductor laserdevices 300 from diverging (an optical system for collimation orconvergence) may be provided on the optical path of the laser light.

Next, see FIG. 7B. FIG. 7B shows the line beam source 214 translatedfrom the position shown in FIG. 7A in the positive direction of theX-axis. The irradiation region 218 is also translated according to themovement of the line beam source 214. In the state of FIG. 7B, the powerof each of the semiconductor laser devices 300 is lower than that in thestate of FIG. 7A. It is not necessary to increase or decrease the powersof respective ones of the semiconductor laser devices 300 at the sametiming. In other words, not only the X-axis direction distribution ofthe irradiation intensity IS but also the Y-axis direction distributioncan be variously changed during the scanning with the line beam.

By using the thus-arranged plurality of semiconductor laser devices 300,the power of the semiconductor laser devices 300 can be temporallyand/or spatially modulated according to the position of the irradiationregion 218. Thus, the distribution of the irradiation intensity acrossthe scanned surface SC can be controlled.

FIG. 8 is a perspective view schematically showing another configurationexample of the line beam source 214 that includes a plurality ofsemiconductor laser devices 300. In this example, the semiconductorlaser devices 300 arranged in two rows have a stagger pattern (staggeredarrangement). By reducing the distance between the centers of the tworows, a single line beam can be formed in total. When the orientation ofthe semiconductor laser devices 300 is adjusted such that the opticalaxes of the semiconductor laser devices 300 included in the first rowand the optical axes of the semiconductor laser devices 300 included inthe second row intersect with each other on the multilayer stack 100,substantially a single line beam can be formed.

According to the “line beam source” of the embodiment of the presentdisclosure, the irradiation region of the lift-off light does not needto be a single line. The irradiation region only needs to becontinuously or discontinuously distributed in a direction transverse tothe scanning direction. In other words, it is only necessary that theline beam source includes a plurality of light sources arranged along aline. The number of such lines is not limited to being singular but maybe two or more.

Next, see FIG. 9. FIG. 9 is a diagram schematically showing an exampleof the distribution in the Y-axis direction of the irradiation intensityof the lift-off light 216. In the graph of FIG. 9, the horizontal axisrepresents the Y-axis coordinate of the irradiation region, and thevertical axis represents the irradiation intensity. The irradiationintensity is expressed by the energy density per unit area (e.g.,[mJ/cm²]). In the graph of FIG. 9, specific numbers of the irradiationintensity are not shown. The irradiation intensity refers to a value inthe range of, for example, not less than 0 mJ/cm² and not more than 500mJ/cm².

A curve shown by a broken line in the graph of FIG. 9 represents thedistribution in the Y-axis direction of the irradiation intensity, I(Y).The Y-axis direction distribution I(Y) of the irradiation intensity isdefined by overlapping of the light intensity distributions of laserlight emitted from the plurality of semiconductor laser devices 300 ofthe line beam source 214 (e.g., FIG. 7A). The light intensitydistribution of the laser light emitted from each of the semiconductorlaser devices 300 can be reshaped using an optical element such as lens.The light intensity distribution shown in the drawing is merelyexemplary. In FIG. 9, a straight dot-chain line represents thresholdlevel Th of the irradiation intensity which is necessary fordelamination. Threshold level Th is, for example, 250-300 mJ/cm². In aregion irradiated with lift-off light at an irradiation intensity lowerthan this threshold level Th, the amount of lift-off light absorbed bythe plastic film 30 is insufficient. Therefore, the plastic film 30 inthat region remains bound, without being delaminated from the glass base10.

In FIG. 9, a cross section of the multilayer stack 100 which is parallelto the YZ plane is shown above the graph for reference. The glass base10 extends from position Y0 to position Y5. The OLED device 1000 on theleft-hand side resides in the region extending from position Y1 toposition Y2. The OLED device 1000 on the right-hand side resides in theregion extending from position Y3 to position Y4. In other words, theflexible substrate regions 30 d of the plastic film 30 correspond to theregion extending from position Y1 to position Y2 and the regionextending from position Y3 to position Y4. Meanwhile, the intermediateregion 30 i of the plastic film 30 corresponds to the region extendingfrom position Y0 to position Y1, the region extending from position Y2to position Y3, and the region extending from position Y4 to positionY5.

In the example of FIG. 9, the irradiation intensity distribution I(Y) ofthe lift-off light is higher than threshold level Th in the regionextending from position Y1 to position Y2 and the region extending fromposition Y3 to position Y4. In other words, the interface between theflexible substrate regions 30 d of the plastic film 30 and the glassbase 10 is irradiated with lift-off light whose irradiation intensityexceeds threshold level Th. Meanwhile, each of the region extending fromposition Y0 to position Y1, the region extending from position Y2 toposition Y3, and the region extending from position Y4 to position Y5includes a portion in which the irradiation intensity distribution I(Y)of the lift-off light is lower than threshold level Th.

The smallest value of the irradiation intensity distribution I(Y) of thelift-off light during the scanning is typically 0 mJ/cm² but may begreater than 0 mJ/cm so long as it is lower than threshold level Th.

When an amorphous semiconductor is heated and crystallized byirradiation with laser light in the shape of a line beam, theirradiation intensity distribution is desired to be uniform in order toachieve uniform crystallinity. On the other hand, when the delaminationin the present embodiment is carried out, the irradiation intensity ofthe line beam does not need to be uniform so long as the irradiationintensity of the lift-off light at the interface which needsdelamination exceeds threshold level Th.

In the example of FIG. 9, the irradiation intensity distribution I(Y) ofthe lift-off light has many peaks, although the embodiment of thepresent disclosure is not limited to such an example. For example, asillustrated in FIG. 10, part of the irradiation intensity distributionI(Y) of the lift-off light may be linear. In the example of FIG. 10, thelight intensity distribution of laser light emitted from each of thesemiconductor laser devices 300 of the line beam source 214 (e.g., FIG.7A) is flat at the center of its optical axis, i.e., “top hat” type. Ifthe irradiation intensity of the lift-off light at the interface whichneeds delamination exceeds threshold level Th as described above, theirradiation intensity of the line beam does not need to be uniform.Thus, the optical powers of the plurality of semiconductor laser devices300 may be different from one another.

According to the present embodiment, in the irradiation intensitydistribution I(Y), the irradiation intensity of laser light for theinterface between the intermediate region 30 i of the plastic film 30and the glass base 10 is lower than the irradiation intensity of laserlight for the interface between the flexible substrate regions 30 d ofthe plastic film 30 and the glass base 10.

FIG. 11 shows an example of the Y-axis direction distribution I(Y) in across section which is different from the Y-axis direction distributionI(Y) shown in FIG. 9. This cross section extends across the protrusions30V and the cutout 30U of the flexible substrate regions 30 d shown inFIG. 1C.

In the cross section shown in FIG. 11, the center of each of two OLEDdevices 1000 includes a portion which is to be bound to the glass base10, without being delaminated together with the intermediate region 30 iof the plastic film 30 from the glass base 10.

In the example of FIG. 11, the power of some of the laser devices thatare constituents of the line beam source 214 is decreased, whereby theY-axis direction distribution I(Y) is made locally lower than thresholdlevel Th at the interface between the intermediate region 30 i of theplastic film 30 and the glass base 10. Of a portion in which theirradiation intensity is lower than threshold level Th, a partcorresponding to the cutout 30U of the flexible substrate region 30 dforms a “large-width portion” in the striped “low irradiation region”.

FIG. 12 shows another example of the Y-axis direction distribution I(Y)in the same cross section as that of FIG. 11. The Y-axis directiondistribution I(Y) of FIG. 12 can be realized by a line beam source 214which includes 27 or more aligned semiconductor laser devices. In thisexample, laser light emitted from each semiconductor laser device canrealize a Y-axis direction distribution I(Y) which changes at a higherspatial resolution than in the example of FIG. 11. Note that at theinterface between the intermediate region 30 i of the plastic film 30and the glass base 10, the irradiation intensity may be zero.

According to the embodiment of the present disclosure, the line beamsource 214 includes a plurality of laser light sources, and therefore,the irradiation intensity in the line beam can be spatially andtemporally modulated by adjusting the power of each laser light source.Thus, a spatial distribution of the irradiation intensity which accordswith the shape, size and arrangement of the OLED devices 1000 includedin the multilayer stack 100 can be easily realized. More specifically,the spatial distribution of the irradiation intensity in the line beamis temporally changed during scanning such that the flexible substrateregions 30 d which have a shape such as shown in, for example, FIG. 1Cor FIG. 1D can be irradiated with lift-off light at an irradiationintensity which is necessary for delamination while the intermediateregion 30 i of the plastic film 30 can be irradiated with lift-off lightat an irradiation intensity which would not cause delamination. If thetype or design of the multilayer stack 100 to be produced is changed,the distribution of the irradiation intensity can be flexibly modulated.

The region in which the irradiation intensity of the lift-off light islower than a level necessary for delamination does not need to includethe entirety of the intermediate region 30 i of the plastic film 30. Theentirety of the unnecessary portions of the multilayer stack 100 can beleft on the glass base 10 so long as part of the intermediate region 30i of the plastic film 30 is bound to the glass base 10. According to theembodiment of the present disclosure, the unnecessary portions of themultilayer stack 100 can be left on the glass base 10 in a wide rangewhich accords with its shape.

A typical example of the laser light source is a semiconductor laserdevice, although the embodiment of the present disclosure is not limitedto this example. When a semiconductor laser device is used, a smallsize, lightweight line beam source can advantageously be realized.However, when the multilayer stack 100 is moved during the scanning,each of a plurality of laser light sources may be a large laser deviceas compared with the semiconductor laser device. When the oscillationwavelength of the laser light source is out of a range suitable fordelamination of the plastic film, the laser light may be converted to aharmonic wave using a wavelength converter.

Next, see FIG. 13. FIG. 13 is a diagram schematically showing an exampleof the distribution in the X-axis direction (scanning direction) of theirradiation intensity of the lift-off light 216. In the graph of FIG.13, the horizontal axis represents the X-axis coordinate of theirradiation position, and the vertical axis represents the irradiationintensity. In the graph of FIG. 13, the solid line represents the X-axisdirection distribution I(X) of the irradiation intensity, and a straightdot-chain line represents threshold level Th of the irradiationintensity which is necessary for delamination.

In FIG. 13, a cross section of the multilayer stack 100 which isparallel to the XZ plane is shown above the graph for reference. Thiscross section is perpendicular to the cross section of FIG. 9. The glassbase 10 extends from position X0 to position X5. The OLED device 1000 onthe left-hand side in the drawing resides in the region extending fromposition X1 to position X2. The OLED device 1000 on the right-hand sideresides in the region extending from position X3 to position X4. Inother words, the flexible substrate regions 30 d of the plastic film 30correspond to the region extending from position X1 to position X2 andthe region extending from position X3 to position X4. Meanwhile, theintermediate region 30 i of the plastic film 30 corresponds to theregion extending from position X0 to position X1 (width: W1), the regionextending from position X2 to position X3 (width: W3), and the regionextending from position X4 to position X5 (width: W2). The intermediateregion 30 i at the left edge of the plastic film 30 in FIG. 13 (width:W1) includes a region in which the irradiation intensity is lower thanthreshold level Th (width: S1). Meanwhile, the intermediate region 30 iat the right edge of the plastic film 30 in FIG. 13 (width: W2) includesa region in which the irradiation intensity is lower than thresholdlevel Th (width: S2). Here, W1>S1 and W2>S2 hold. It is preferred thatwidth S1 is not less than 50% of width W1 and width S2 is not less than50% of width W2.

The X-axis direction distribution I(X) of the irradiation intensityrepresents the whole scanning (sum or integral value) of the lift-offlight. For example, while the irradiation position of the lift-off light(the position of the center line of the line beam) moves from positionX0 to position X1, the region extending from position X1 to position X5is not irradiated with the lift-off light. In this period, theirradiation intensity of the lift-off light in the region extending fromposition X1 to position X5 is, as a matter of course, zero.

The line width (the transverse axis dimension, the size in the X-axisdirection) of the lift-off light 216 can be, for example, about 0.2 mm.This dimension defines the largeness of the irradiation region at theinterface between the plastic film 30 and the glass base 10 at a certaintime. The lift-off light 216 can be emitted in the form of a pulsed orcontinuous wave. Irradiation with the pulsed wave can be carried out atthe frequency (the number of shots in one second) of, for example, about200 times per second. When the lift-off light 216 is a pulsed wave, thescanning speed is determined such that two consecutive shots formpartially-overlapping irradiation regions. If, for example, the linewidth (the transverse axis dimension, the size in the X-axis direction)of the lift-off light 216 is 0.2 mm and the irradiation position movesat 20 mm per second in the X-axis direction, a gap can occur betweenneighboring shots so long as the number of shots per second is less than100. Therefore, the number of shots per second needs to exceed 100.

The positioning accuracy of the irradiation position depends on themechanical forwarding accuracy of the line beam source 214. When theline width (the transverse axis dimension, the size in the X-axisdirection) of the lift-off light 216 is, for example, 40 μm, moving theline beam source 214 stepwise at intervals of 20 μm can set the overlapof irradiation regions formed by two consecutive shots to 50%. Movingthe line beam source 214 stepwise at intervals of 30 μm can set theoverlap of irradiation regions formed by two consecutive shots to 75%.By controlling the overlap of irradiation regions, the irradiationintensity can also be changed without modulating the power of the laserlight source.

When the irradiation position of the lift-off light is forwardedstepwise, “stepwise movement of the line beam source 214” and “pulsedirradiation with the lift-off light” can be repeated. In this case,irradiation with the lift-off light can be carried out while movement ofthe line beam source 214 relative to the stage 210 is stopped. Inirradiation of a stationary object with laser light, adjustment of theirradiation intensity to a target value is easier than in irradiation ofa moving object with laser light. For example, the irradiation intensitycan be adjusted by, for example, increasing or decreasing the number ofirradiation pulses or the irradiation duration at a stationary position.According to the embodiment of the present disclosure, a semiconductorlaser device is used for the light source, and therefore,advantageously, the irradiation intensity can be easily controlled byadjusting the oscillation state of the semiconductor laser device.

When the moving speed (scanning speed) of the irradiation position isfixed to a predetermined value, the irradiation intensity can bemodulated by increasing or decreasing the number of shots per second. Onthe contrary, when the number of shots per second is fixed, theirradiation intensity can be modulated by increasing or decreasing themoving speed (scanning speed) of the irradiation position. Theirradiation intensity can also be modulated by changing the otherparameters, e.g., the optical distance from the line beam source 214 tothe multilayer stack 100. Also, a low irradiation region can be formedby providing a mechanical shutter between the line beam source 214 andthe glass base 10 such that this shutter blocks the optical path of thelift-off light.

As seen from FIG. 13, in this example, the irradiation intensity oflift-off light for at least part of the interface between theintermediate region 30 i of the plastic film 30 and the glass base 10 islower than the irradiation intensity of lift-off light for the interfacebetween the flexible substrate regions 30 d of the plastic film 30 andthe glass base 10. The region of this “at least part” may be referred toas “low irradiation region” or “non-delamination region”. In the exampleof FIG. 13, the low irradiation region includes two parallel striperegions extending along the perimeter of the glass base 10 (a region ofwidth S1 and a region of width 32). The two stripe regions can be formedby irradiation with weak lift-off light 216 shown in FIG. 5A and FIG.5D. In these two stripe regions, the irradiation intensity of thelift-off light 216 is lower than threshold level Th, and therefore, theintermediate region 30 i of the plastic film 30 remains bound to theglass base 10.

As previously described with reference to FIG. 9 and FIG. 11, in theembodiment of the present disclosure, the distribution in the Y-axisdirection of the irradiation intensity is changed while the irradiationposition of the lift-off light is moved along the X-axis (duringscanning). Thus, any of the stripe regions which define the “lowirradiation region” can include a large-width portion and/ornarrow-width portion which accords with the intermediate region 30 i ofthe plastic film 30. By thus making the shape and size of the “lowirradiation region” conformable to those of the intermediate region 30 iof the plastic film 30, the degree of adhesion between the intermediateregion 30 i of the plastic film 30 and the glass base 10 can be improvedas a whole. It is not desired that the “low irradiation region” extendsbeyond the intermediate region 30 i of the plastic film 30 into theflexible substrate regions 30 d.

FIG. 14 shows an example where the irradiation intensity is temporarilylower than threshold level Th in the middle of the scanning with thelift-off light 216. Specifically, the irradiation intensity is lowerthan threshold level Th in part of the region extending from position X2to position X3 (width: S3). In this example, the “low irradiationregion” at the interface between the intermediate region 30 i of theplastic film 30 and the glass base 10 includes not only the two striperegions but also a single middle stripe region (width: S3) which isparallel to the two stripe regions. Each of widths S1, S2, S3 of thesestripe regions is, for example, not less than 1 mm and, in a certainexample, not less than 3 mm.

In the examples of FIG. 13 and FIG. 14, two OLED devices 1000 arearranged in the direction of the X-axis. When N is an integer not lessthan 3 and N OLED devices 1000 are arranged in the direction of theX-axis, the total number of stripes formed by the intermediate region 30i lying between two adjoining OLED devices 1000 is N−1. It is notnecessary to provide a low irradiation region in all of the N−1 stripes.Alternatively, a plurality of low irradiation regions may be providedfor an intermediate region 30 i which forms a single stripe.

In the examples of FIG. 13 and FIG. 14, the low irradiation region ofwidth S1 and the low irradiation region of width S2 each reach theperimeter of the plastic film 30, although the embodiment of the presentdisclosure is not limited to this example. For example, the lowirradiation region can be in various forms as shown in FIG. 15A and FIG.15B. FIG. 15A and FIG. 15B are diagrams schematically showing stillother examples of the distribution in the X-axis direction of theirradiation intensity of the lift-off light. In these drawings, examplesof the modulation pattern of the irradiation intensity at the interfacebetween the intermediate region 30 i surrounding the OLED device 1000 onthe left-hand side of FIG. 13 and the glass base 10 are shown.

In the example shown in FIG. 15A, the striped low irradiation regions(width: S1) extending along the perimeter of the plastic film 30 do notreach the perimeter of the plastic film 30. The irradiation intensity ofthe lift-off light may exceed threshold level Th before the glass base10 is irradiated with the lift-off light. As in the region extendingfrom position X1 to position X3 shown in FIG. 15A, the irradiationintensity may gradually change. When the irradiation intensity graduallychanges, the width (the size in the scanning direction) of the “lowirradiation region” can be defined as the width of a region in which theirradiation intensity is lower than threshold level Th.

In the example shown in FIG. 15B, the low irradiation region consists ofa plurality of stripes which have a relatively narrow width. When thelift-off light is, for example, pulsed light, such a low irradiationregion can be realized by applying consecutive shots such thatirradiation regions do not overlap each other.

To maintaining at least part of the intermediate region 30 i of theplastic film 30 bound to the glass base 10 by relatively decreasing theirradiation intensity, it is desirable that the irradiation intensity inthe “at least part” is lower than threshold level. Th. However, even ifit is not lower than threshold level Th, the intermediate region 30 i islikely to remain on the glass base 10 so long as an irradiationintensity which is lower than the irradiation intensity in a region tobe delaminated is realized. If the difference between the irradiationintensity in a region to be delaminated and the irradiation intensity inthe low irradiation region is not less than 50 mJ/cm², a sufficienteffect is achieved.

In the present embodiment, the lift-off light is a line beam extendingin a direction parallel to the perimeter of the glass base 10 (firstdirection), and the scanning direction is the second direction which isperpendicular to the first direction. However, the first direction andthe second direction do not need to be perpendicular to each other butonly need to be transverse to each other.

In the above-described example, as previously described with referenceto FIG. 4, the position of the line beam source 214 is moved while thestage 210 is fixed, whereby the irradiation position of the lift-offlight is moved (scanning). However, the embodiment of the presentinvention is not limited to this example. Scanning with the lift-offlight may be carried out by moving the stage 210 while the line beamsource 214 is fixed. Alternatively, scanning with the lift-off light maybe carried out by moving both the line beam source 214 and the stage210.

<Lift-Off>

FIG. 16A illustrates a state where the multilayer stack 100 is incontact with the stage 210 after irradiation with the lift-off light.While this state is maintained, the distance from the stage 210 to theglass base 10 is increased. At this point in time, the stage 210 of thepresent embodiment holds an OLED device portion of the multilayer stack100.

An unshown actuator holds the glass base 10 and moves the entirety ofthe glass base 10 in the direction of arrow L, thereby carrying outdelaminating (lift-off). The glass base 10 can be moved together with anunshown chuck stage while being adhered by suction to the chuck stage.The direction of movement of the glass base 10 does not need to bevertical, but may be diagonal, to the first surface 100 a of themultilayer stack 100. The movement of the glass base 10 does not need tobe linear but may be rotational. Alternatively, the stage 210 may bemoved upward in the drawing while the glass base 10 is secured by anunshown holder or another stage.

FIG. 16B is a cross-sectional view showing the thus-separated firstportion 110 and second portion 120 of the multilayer stack 100. FIG. 17is a perspective view showing the second portion 120 of the multilayerstack 100. In FIG. 17, a guide rail 246 and other relevant componentsare not shown, and the shape of the intermediate region 30 i issimplified such that the recesses and protrusions are not shown. Thefirst portion 110 of the multilayer stack 100 includes a plurality ofOLED devices 1000 which are in contact with the stage 210. Therespective OLED devices 1000 include the functional layer regions 20 andthe plurality of flexible substrate regions 30 d of the plastic film 30.Meanwhile, the second portion 120 of the multilayer stack 100 includesthe glass base 10 and the intermediate region 30 i of the plastic film30. The intermediate region 30 i of the plastic film 30 is bound to theglass base 10 in at least some low-irradiation regions. Thus, theentirety of the intermediate region 30 i of the plastic film 30separates from the stage 210 while the entirety of the intermediateregion 30 i is kept adhered to the glass base 10.

In the example of FIG. 17, both the irradiation process with thelift-off light and the delaminating process are carried out using theLLO unit 220 that includes the stage 210. The embodiment of the presentdisclosure is not limited to this example. The irradiation process withthe lift-off light may be carried out using a lift-off light irradiationunit which includes the stage 210, while the delaminating process iscarried out using a different apparatus that includes another stagewhich is different from the stage 210. In this case, after irradiationwith the lift-off light, it is necessary to transfer the multilayerstack 100 from the stage 210 to another unshown stage. When the samestage is used for carrying out both the irradiation process with thelift-off light and the delaminating process, the step of transferringthe multilayer stack between the stages can be omitted.

As described above, in the present embodiment, the step of separatingthe multilayer stack 100 into the first portion 110 and the secondportion 120 is carried out while the stage 210 holds the second surface100 b of the multilayer stack 100 by suction. The essence of thisseparation step resides in that an unnecessary part of the multilayerstack 100 which is not a constituent of the OLED device 1000 separatestogether with the glass base 10 from the stage 210. In the presentembodiment, the cutting step illustrated in FIG. 2, i.e., the step ofcutting a part of the multilayer stack 100 exclusive of the glass base10 into the plurality of OLED devices 1000 and the remaining unnecessaryportions, is carried out before irradiation with the lift-off light.Carrying out the cutting step before the lift-off light irradiation stepis effective in realizing the separation illustrated in FIG. 16B andFIG. 17. In order that an unnecessary portion which is not a constituentof the OLED device 1000 remains on the glass base 10, the irradiationintensity of the lift-off light is modulated such that part of thatunnecessary portion is kept bound to the glass base 10.

<Steps after Delaminating>

FIG. 18 is a perspective view showing the first portion 110 (OLEDdevices 1000) of the multilayer stack 100 adhered by suction to thestage 210 and the second portion 120 (the glass base 10 and objectsbound thereto) at a position distant from the stage 210. Unnecessaryportions of the multilayer stack 100 which are not constituents of theOLED devices 1000 are bound to the glass base 10.

FIG. 19 is a perspective view showing the first portion 110 of themultilayer stack 100 adhered by suction to the stage 210. The firstportion 110 of the multilayer stack 100 supported by the stage 210includes a plurality of OLED devices 1000 arrayed in rows and columns.In the example of FIG. 19, a part of the plastic film 30, specificallythe surface (delaminated surface) 30 s of the flexible substrate regions30 d, is exposed.

According to the present embodiment, the OLED devices 1000 can beappropriately separated from the remaining unnecessary portions evenwhen the OLED devices 1000 and the flexible substrate regions 30 d ofthe plastic film 30 which function as the flexible substrates for theOLED devices 1000 have complicated planar shapes such as those shown inFIG. 1A and other drawings. As previously described, this is realized bytemporally changing the spatial distribution of the irradiationintensity of the lift-off light during scanning with the lift-off lightsuch that an irradiation intensity which is necessary for delaminationis selectively applied to the flexible substrate regions 30 d of theplastic film 30. As a result, the entirety of the intermediate region 30i of the plastic film 30 can be kept bound to the glass base 10.

FIG. 20 is a cross-sectional view showing that the stage 210 holds theOLED devices 1000 by suction. This cross section is parallel to the ZXplane. The direction of the Z-axis of FIG. 20 is opposite to thedirection of the Z-axis of FIG. 18 and FIG. 19.

Various processes can be sequentially or concurrently performed on theplurality of OLED devices 1000 which are in contact with the stage 210.

The “processes” to be performed on the OLED devices 1000 can includeattaching a dielectric and/or electrically-conductive film to each ofthe plurality of OLED devices 1000, cleaning or etching each of theplurality of OLED devices 1000, and mounting an optical part and/or anelectronic part to each of the plurality of OLED devices 1000.Specifically, a part such as, for example, a polarizer, encapsulationfilm, touchscreen, heat radiation sheet, electromagnetic shield, driverintegrated circuit, or the like, can be mounted to the flexiblesubstrate region 30 d of each of the OLED devices 1000. The sheet-likepart includes a functional film which can add an optical, electrical ormagnetic function to the OLED devices 1000.

The plurality of OLED devices 1000 are supported by the stage 210 suchthat the OLED devices 1000 are adhered by suction to the stage 210. Thevarious processes which are to be performed on each of the OLED devices1000 can be efficiently carried out.

The surface 30 s of the plastic film 30 delaminated from the glass base10 is active. Therefore, the surface 30 s may be covered with aprotection film or subjected to a surface treatment for conversion to ahydrophobic surface before various parts are mounted to the surface 30s.

FIG. 21 is a cross-sectional view schematically showing the OLED devices1000 detached from the stage 210 after the sheet-like part (functionalfilm) 60 is mounted to the OLED devices 1000.

According to the prior art, the plastic film is delaminated from theglass base before the OLED devices 1000 are divided from one another.Therefore, when a subsequent process is carried out, a large number ofOLED devices 1000 are bound to a single plastic film. Thus, it isdifficult to carry out an efficient process on each of the OLED devices1000. When the OLED devices 1000 are divided from one another after thesheet-like part is attached, a portion of the sheet-like part which ispresent in an intermediate region between adjoining two of the OLEDdevices 1000 is useless.

On the other hand, according to the embodiment of the presentdisclosure, a large number of OLED devices 1000 are still orderlyarrayed on the stage 210 after being delaminated from the glass base 10.Therefore, various processes can be efficiently performed on the OLEDdevices 1000 sequentially or concurrently.

After the step of separating the multilayer stack 100 into the firstportion 110 and the second portion 120, the step of adhering anotherprotection sheet (second protection sheet) 70 to the plurality of OLEDdevices 1000 which are in contact with the stage 210 may be furtherperformed as shown in FIG. 22. The second protection sheet 70 canperform the function of temporarily protecting the surface of theflexible substrate regions 30 d of the plastic film 30 delaminated fromthe glass base 10. The second protection sheet 70 can have the samelaminate structure as that of the previously-described protection sheet50. The protection sheet 50 can be referred to as “first protectionsheet 50”.

The second protection sheet 70 may be adhered to the plurality of OLEDdevices 1000 after various processes which have previously beendescribed are performed on the plurality of OLED devices 1000 which arein contact with the stage 210.

When suction of the OLED devices 1000 by the stage 210 is stopped afterthe second protection sheet 70 is adhered, the plurality of OLED devices1000 which are bound to the second protection sheet 70 can be detachedfrom the stage 210. Thereafter, the second protection sheet 70 canfunction as a carrier for the plurality of OLED devices 1000. This istransfer of the OLED devices 1000 from the stage 210 to the secondprotection sheet 70. Various processes may be sequentially orconcurrently performed on the plurality of OLED devices 1000 which arebound to the second protection sheet 70.

FIG. 23 is a cross-sectional view showing a carrier sheet 90 carrying aplurality of parts (functional films) 80 which are to be mounted to theplurality of OLED devices 1000. By moving this carrier sheet 90 in thedirection of arrow U, the respective parts 80 can be attached to theOLED devices 1000. The upper surface of the parts 80 has an adhesivelayer which is capable of strongly adhering to the OLED devices 1000.Meanwhile, the adhesion between the carrier sheet 90 and the parts 80 isrelatively weak. Using such a carrier sheet 90 enables a simultaneous“transfer” of the parts 80. Such a transfer is readily realized becausethe plurality of OLED devices 1000 are regularly arrayed on the stage210 while the OLED devices 1000 are supported by the stage 210.

Multilayer Stack

Hereinafter, the configuration of the multilayer stack 100 before thecutting of FIG. 2 is described in more detail.

First, see FIG. 24A. FIG. 24A is a cross-sectional view showing theglass base 10 with the plastic film 30 provided on the surface of theglass base 10. The glass base 10 is a supporting substrate forprocesses. The thickness of the glass base 10 can be, for example, about0.3-0.7 mm.

In the present embodiment, the plastic film 30 is a polyimide filmhaving a thickness of, for example, not less than 5 μm and not more than100 μm. The polyimide film can be formed from a polyamide acid, which isa precursor of polyimide, or a polyimide solution. The polyimide filmmay be formed by forming a polyamide acid film on the surface of theglass base 10 and then thermally imidizing the polyamide acid film.Alternatively, the polyimide film may be formed by forming, on thesurface of the glass base 10, a film from a polyimide solution which isprepared by melting a polyimide or dissolving a polyimide in an organicsolvent. The polyimide solution can be obtained by dissolving a knownpolyimide in an arbitrary organic solvent. The polyimide solution isapplied to the surface 10 s of the glass base 10 and then dried, wherebya polyimide film can be formed.

In the case of a bottom emission type flexible display, it is preferredthat the polyimide film realizes high transmittance over the entirerange of visible light. The transparency of the polyimide film can berepresented by, for example, the total light transmittance in accordancewith JIS K7105-1981. The total light transmittance can be set to notless than 80% or not less than 85%. On the other hand, in the case of atop emission type flexible display, it is not affected by thetransmittance.

The plastic film 30 may be a film which is made of a synthetic resinother than polyimide. Note that, however, in the embodiment of thepresent disclosure, the process of forming a thin film transistorincludes a heat treatment at, for example, not less than 350° C., andtherefore, the plastic film 30 is made of a material which will not bedeteriorated by this heat treatment.

The plastic film 30 may be a multilayer structure including a pluralityof synthetic resin layers. In one form of the present embodiment, indelaminating a flexible display structure from the glass base 10, laserlift-off is carried out such that the plastic film 30 is irradiated withultraviolet laser light transmitted through the glass base 10. A part ofthe plastic film 30 at the interface with the glass base 10 needs toabsorb the ultraviolet laser light and decompose (disappear).Alternatively, for example, a sacrificial layer (thin metal or amorphoussilicon layer) which is to absorb laser light of a certain wavelengthband and produce a gas may be provided between the glass base 10 and theplastic film 30. In this case, the plastic film 30 can be easilydelaminated from the glass base 10 by irradiating the sacrificial layerwith the laser light. Providing the sacrificial layer also achieves theeffect of suppressing generation of ashes.

<Polishing>

When there is an object (target) which is to be polished away, such asparticles or protuberances, on the surface 30 x of the plastic film 30,the target may be polished away using a polisher such that the surfacebecomes flat. Detection of a foreign object, such as particles, can berealized by, for example, processing of an image obtained by an imagesensor. After the polishing process, a planarization process may beperformed on the surface 30 x of the plastic film 30. The planarizationprocess includes the step of forming a film which improves the flatness(planarization film) on the surface 30 x of the plastic film 30. Theplanarization film does not need to be made of a resin.

<Lower Gas Barrier Film>

Then, a gas barrier film may be formed on the plastic film 30. The gasbarrier film can have various structures. Examples of the gas barrierfilm include a silicon oxide film and a silicon nitride film. Otherexamples of the gas barrier film can include a multilayer film includingan organic material layer and an inorganic material layer. This gasbarrier film may be referred to as “lower gas barrier film” so as to bedistinguishable from a gas barrier film covering the functional layerregions 20, which will be described later. The gas barrier film coveringthe functional layer regions 20 can be referred to as “upper gas barrierfilm”.

<Functional Layer Region>

Hereinafter, the process of forming the functional layer regions 20,including the TFT layer 20A and the OLED layer 20B, and the upper gasbarrier film 40 is described.

First, as shown in FIG. 24B, a plurality of functional layer regions 20are formed on a glass base 10. There is a plastic film 30 between theglass base 10 and the functional layer regions 20. The plastic film 30is bound to the glass base 10.

More specifically, the functional layer regions 20 include a TFT layer20A (lower layer) and an OLED layer 20B (upper layer). The TFT layer 20Aand the OLED layer 20B are sequentially formed by a known method. TheTFT layer 20A includes a circuit of a TFT array which realizes an activematrix. The OLED layer 20B includes an array of OLED elements, each ofwhich can be driven independently. The thickness of the TFT layer 20Ais, for example, 4 μm. The thickness of the OLED layer 20B is, forexample, 1 μm.

FIG. 25 is a basic equivalent circuit diagram of a sub-pixel in anorganic EL (Electro Luminescence) display. A single pixel of the displaycan consist of sub-pixels of different colors such as, for example, R(red), G (green), and B (blue). The example illustrated in FIG. 25includes a selection TFT element Tr1, a driving TFT element Tr2, astorage capacitor CH, and an OLED element EL. The selection TFT elementTr1 is connected with a data line DL and a selection line SL. The dataline DL is a line for transmitting data signals which define an image tobe displayed. The data line DL is electrically coupled with the gate ofthe driving TFT element Tr2 via the selection TFT element Tr1. Theselection line SL is a line for transmitting signals for controlling theON/OFF state of the selection TFT element Tr1. The driving TFT elementTr2 controls the state of the electrical connection between a power linePL and the OLED element EL. When the driving TFT element Tr2 is ON, anelectric current flows from the power line PL to a ground line GL viathe OLED element EL. This electric current allows the OLED element EL toemit light. Even when the selection TFT element Tr1 is OFF, the storagecapacitor CH maintains the ON state of the driving TFT element Tr2.

The TFT layer 20A includes a selection TFT element Tr1, a driving TFTelement Tr2, a data line DL, and a selection line SL. The OLED layer 20Bincludes an OLED element EL. Before formation of the OLED layer 20B, theupper surface of the TFT layer 20A is planarized by an interlayerinsulating film that covers the TFT array and various wires. A structurewhich supports the OLED layer 20B and which realizes active matrixdriving of the OLED layer 20B is referred to as “backplane”.

The circuit elements and part of the lines shown in FIG. 25 can beincluded in any of the TFT layer 20A and the OLED layer 20B. The linesshown in FIG. 25 are connected with an unshown driver circuit.

In the embodiment of the present disclosure, the TFT layer 20A and theOLED layer 20B can have various specific configurations. Theseconfigurations do not limit the present disclosure. The TFT elementincluded in the TFT layer 20A may have a bottom gate type configurationor may have a top gate type configuration. Emission by the OLED elementincluded in the OLED layer 20B may be of a bottom emission type or maybe of a top emission type. The specific configuration of the OLEDelement is also arbitrary.

The material of a semiconductor layer which is a constituent of the TFTelement includes, for example, crystalline silicon, amorphous silicon,and oxide semiconductor. In the embodiment of the present disclosure,part of the process of forming the TFT layer 20A includes a heattreatment step at 350° C. or higher for the purpose of improving theperformance of the TFT element.

<Upper Gas Barrier Film>

After formation of the above-described functional layer, the entirety ofthe functional layer regions 20 is covered with a gas barrier film(upper gas barrier film) 40 as shown in FIG. 24C. A typical example ofthe upper gas barrier film 40 is a multilayer film including aninorganic material layer and an organic material layer. Elements such asan adhesive film, another functional layer which is a constituent of atouchscreen, polarizers, etc., may be provided between the upper gasbarrier film 40 and the functional layer regions 20 or in a layeroverlying the upper gas barrier film 40. Formation of the upper gasbarrier film 40 can be realized by a Thin Film Encapsulation (TFE)technique. From the viewpoint of encapsulation reliability, the WVTR(Water Vapor Transmission Rate) of a thin film encapsulation structureis typically required to be not more than 1×10⁻⁴ g/m²/day. According tothe embodiment of the present disclosure, this criterion is met. Thethickness of the upper gas barrier film 40 is, for example, not morethan 1.5 μm.

FIG. 26 is a perspective view schematically showing the upper surfaceside of the multilayer stack 100 at a point in time when the upper gasbarrier film 40 is formed. A single multilayer stack 100 includes aplurality of OLED devices 1000 supported by the glass base 10. In theexample illustrated in FIG. 26, a single multilayer stack 100 includes alarger number of functional layer regions 20 than in the exampleillustrated in FIG. 1A. As previously described, the number offunctional layer regions 20 supported by a single glass base 10 isarbitrary.

<Protection Sheet>

Next, refer to FIG. 24D. As shown in FIG. 24D, a protection sheet 50 isadhered to the upper surface of the multilayer stack 100. The protectionsheet 50 can be made of a material such as, for example, polyethyleneterephthalate (PET), polyvinyl chloride (PVC), or the like. Aspreviously described, a typical example of the protection sheet 50 has alaminate structure which includes a layer of an applied mold-releasingagent at the surface. The thickness of the protection sheet 50 can be,for example, not less than 50 μm and not more than 200 μm.

After the thus-formed multilayer stack 100 is provided, the productionmethod of the present disclosure can be carried out using theabove-described production apparatus (LLO unit 220).

INDUSTRIAL APPLICABILITY

An embodiment of the present invention provides a novel flexible OLEDdevice production method. A flexible OLED device is broadly applicableto smartphones, tablet computers, on-board displays, and small-, medium-and large-sized television sets.

REFERENCE SIGNS LIST

-   10 . . . glass base, 20 . . . functional layer region, 20A . . . TFT    layer, 20B . . . OLED layer, 30 . . . plastic film, 30 d . . .    flexible substrate region of plastic film, 30 i . . . intermediate    region of plastic film, 40 . . . gas barrier film, 50 . . .    protection sheet, 100 . . . multilayer stack, 210 . . . stage, 220 .    . . LLO unit, 260 . . . controller, 300 . . . semiconductor laser    device, 1000 . . . OLED device

The invention claimed is:
 1. A method for producing a flexible OLEDdevice, comprising: providing a multilayer stack which has a firstsurface and a second surface, the multilayer stack including a glassbase which defines the first surface, a functional layer regionincluding a TFT layer and an OLED layer, a synthetic resin film providedbetween the glass base and the functional layer region and bound to theglass base, the synthetic resin film including a flexible substrateregion supporting the functional layer region and an intermediate regionsurrounding the flexible substrate region, and a protection sheet whichcovers the functional layer region and which defines the second surface;dividing the intermediate region and the flexible substrate region ofthe synthetic resin film from each other; irradiating an interfacebetween the synthetic resin film and the glass base with laser light;and separating the multilayer stack into a first portion and a secondportion by increasing a distance from a stage to the glass base whilethe second surface of the multilayer stack is kept in contact with thestage, wherein the first portion of the multilayer stack includes anOLED device which is in contact with the stage, the OLED deviceincluding the functional layer region and the flexible substrate regionof the synthetic resin film, the second portion of the multilayer stackincludes the glass base and the intermediate region of the syntheticresin film, and irradiating the interface between the synthetic resinfilm and the glass base with the laser light includes forming the laserlight from a plurality of arranged laser light sources and temporallyand spatially modulating a power of the plurality of laser light sourcesaccording to a shape of the flexible substrate region of the syntheticresin film such that an irradiation intensity of the laser light for atleast part of an interface between the intermediate region of thesynthetic resin film and the glass base is lower than an irradiationintensity of the laser light for the interface between the flexiblesubstrate region of the synthetic resin film and the glass base.
 2. Themethod of claim 1, wherein a shape of the flexible substrate region ofthe synthetic resin film has a cutout, a protrusion, and/or a curvedcontour when viewed in a direction perpendicular to the first surface.3. The method of claim 1, wherein a number of the flexible substrateregion of the synthetic resin film is plural, and a number of the OLEDdevice included in the first portion of the multilayer stack is plural.4. The method of claim 1, wherein the plurality of laser light sourcesare a plurality of semiconductor laser devices, and irradiating theinterface between the synthetic resin film and the glass base with thelaser light includes modulating a driving current flowing through eachof the plurality of semiconductor laser devices, thereby temporally andspatially modulating the irradiation intensity of the laser light. 5.The method of claim 4, wherein the plurality of semiconductor laserdevices are arranged in a single row or a plurality of rows, and anarrangement pitch of the plurality of semiconductor laser devices is ina range of not less than 1 mm and not more than 5 mm.
 6. The method ofclaim 1, wherein the laser light is a line beam extending in a firstdirection which is parallel to a perimeter of the glass base, andirradiating the interface between the synthetic resin film and the glassbase with the laser light includes moving an irradiation region on theinterface which is to be irradiated with the laser light in a seconddirection which is transverse to the first direction.
 7. The method ofclaim 6, wherein the at least part of the interface between theintermediate region of the synthetic resin film and the glass baseincludes a plurality of parallel stripe regions extending in the firstdirection, and any of the plurality of parallel stripe regions includesa large-width portion and/or a narrow-width portion.
 8. The method ofclaim 6, wherein the at least part of the interface between theintermediate region of the synthetic resin film and the glass baseincludes a plurality of parallel stripe regions extending in the seconddirection, and any of the plurality of parallel stripe regions includesa large-width portion and/or a narrow-width portion.
 9. The method ofclaim 1, wherein the at least part of the interface between theintermediate region of the synthetic resin film and the glass base has awidth which is not less than 50% of a width of the intermediate region.10. The method of claim 1, wherein the at least part of the interfacebetween the intermediate region of the synthetic resin film and theglass base has a width which is not less than 1 mm.
 11. The method ofclaim 1, wherein the difference between an irradiation intensity of thelaser light in the at least part of the interface between theintermediate region of the synthetic resin film and the glass base andan irradiation intensity of the laser light for the interface betweenthe flexible substrate region of the synthetic resin film and the glassbase is not less than 50 mJ/cm².
 12. The method of claim 1 furthercomprising, after separating the multilayer stack into the first portionand the second portion, performing a process on the OLED device which isin contact with the stage.
 13. An apparatus for producing a flexibleOLED device, comprising: a stage for supporting a multilayer stack whichhas a first surface and a second surface, the multilayer stack includinga glass base which defines the first surface, a functional layer regionincluding a TFT layer and an OLED layer, a synthetic resin film providedbetween the glass base and the functional layer region and bound to theglass base, the synthetic resin film including a flexible substrateregion supporting the functional layer region and an intermediate regionsurrounding the flexible substrate region, and a protection sheet whichcovers the functional layer region and which defines the second surface,the intermediate region and the flexible substrate region of thesynthetic resin film being divided from each other; and a lift-off lightirradiation unit for irradiating with laser light an interface betweenthe synthetic resin film and the glass base in the multilayer stacksupported by the stage, wherein the lift-off light irradiation unitincludes a plurality of arranged laser light sources for forming thelaser light, and the lift-off light irradiation unit temporally andspatially modulates a power of the plurality of laser light sourcesaccording to a shape of the flexible substrate region of the syntheticresin film such that an irradiation intensity of the laser light for atleast part of an interface between the intermediate region of thesynthetic resin film and the glass base is lower than an irradiationintensity of the laser light for the interface between the flexiblesubstrate region of the synthetic resin film and the glass base, theapparatus further comprising an actuator for increasing a distance fromthe stage to the glass base while the stage is kept in contact with thesecond surface of the multilayer stack after the interface between thesynthetic resin film and the glass base in the multilayer stack areirradiated with the laser light, thereby separating the multilayer stackinto a first portion and a second portion, wherein the first portion ofthe multilayer stack includes an OLED device which is in contact withthe stage, the OLED device including the functional layer region and theflexible substrate region of the synthetic resin film, and the secondportion of the multilayer stack includes the glass base and theintermediate region of the synthetic resin film.
 14. The apparatus ofclaim 13, wherein the plurality of laser light sources are a pluralityof semiconductor laser devices, and the lift-off light irradiation unitincludes a laser driving circuit for modulating a driving currentflowing through each of the plurality of semiconductor laser devices,thereby temporally and spatially modulating the irradiation intensity ofthe laser light.
 15. The apparatus of claim 14, wherein the plurality ofsemiconductor laser devices are arranged in a single row or a pluralityof rows, and an arrangement pitch of the plurality of semiconductorlaser devices is in a range of not less than 1 mm and not more than 5mm.